The Aztecs, Maya and other pre-Columbian human groups in Mexico and Central America, for example, were excellent farmers and didn’t even know about growing coca.

The Quechua and Aymara were capable of producing nutritious foods on perfect terraces that followed the mountain level curves. On the high plateaux that often exceeded three or four thousand metres in altitude, they grew quinua, a cereal rich in protein, and potatoes.… | more…